Sims 3 won't work on windows 11

xman_iceman​  Please create a new admin Windows account and try playing there.  Make it local, as in, don't link it to your Microsoft account or any email address.  (You can skip that step and answer some security questions instead.)  You'll be able to at least try to launch the game without reinstalling it.

If you still can't play, please look again for any Reliability Monitor errors that happened at the time you tried to open Sims 3, whether those errors list the game or not.

No errors at all strongly suggest the game is being blocked rather than crashing, so the next place to look would be your antivirus.  If you use a third-party program, the simplest test is to temporarily disable it, repair the game (EA App > Sims 3 > Manage > Repair) to undo any changes the AV made, and try again to play.  As long as you don't do anything else at the same time, your computer should be safe.

For Windows Defender, Controlled Folder Access isn't usually a problem for Sims 4, but I suppose it could be if it updated to be more aggressive in blocking access to Documents.  So temporarily disabling it would be the way to test here too.  Please also see whether Smart App Control is active.  It blocked Sims 4 for a few days a couple months ago, and while I didn't see any evidence it was affecting Sims 3, it's supposed to be evolving and getting smarter, so that could also mean it's tightening its restrictions.